Suppose you sample 19 high school baseball pitchers and find that they have an average pitching...

Suppose you sample 19 high school baseball pitchers and find that they have an average pitching speed of 87 miles per hour with a standard deviation of 0.98 mph. Find a 95% confidence interval for the average pitching speed of all high school baseball pitchers. Assume that the population is normally distributed.

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Expert Solution

Solution :

sample size = n = 19

Degrees of freedom = df = n - 1 = 18

t /2,df = 2.101

Margin of error = E = t/2,df * (s / $\sqrt$ n)

= 2.101 * (0.98 / $\sqrt$ 19)

Margin of error = E = 0.5

The 95% confidence interval estimate of the population mean is,

- E < < + E

87 - 0.5 < < 87 + 0.5

86.5 < < 87.5

(86.5, 87.5)

orchestra answered 1 year ago

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